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Clearing the Air: EPA ready to set urea guidelines

DETROIT -- For the first time, the EPA is ready to hand drivers the responsibility for making sure a vehicle's emissions system works properly.

All emissions systems now are passive and require no owner maintenance. But if urea systems are used to remove NOx from diesel exhausts, the EPA says drivers will have to get involved.

Urea injection is expected to be used on diesel-powered cars and trucks starting in 2010. The EPA guidelines will be issued in the next few weeks.

The rules will address the main problem regulators have with urea: The system won't work unless an on-board urea tank is replenished. Otherwise, the car won't meet emissions standards.

The EPA is considering rules that will require the vehicle to eventually stop running if drivers don't keep the tank filled.

Karl Simon, the EPA's assistant director for the office of transportation and air quality, said the agency is focusing on an early-warning system that notifies drivers when the urea tank is low.

The agency also is considering an inducement that forces drivers to refill the urea tank - for example, preventing the engine from starting if the tank is empty or automatically locking the fuel filler door until the urea supply is replenished.

The agency says automakers will have to make it easy for drivers and technicians to identify the urea tank and refill it.

Areas of focus

Simon says the EPA also is focusing on:

Ensuring the urea system is tamperproof and can't be disabled. Since urea is injected into the vehicle's exhaust system, the engine runs normally without it.

Assuring that the system works in cold weather. Urea freezes at about 11 degrees Fahrenheit.

Widespread availability of urea. It could be sold at auto parts stores, quick lube shops, dealership service departments and gas stations.

Assurance that the urea refill interval is at least as long as the manufacturer's oil change interval so both items can serviced at the same time by the dealership.

DaimlerChrysler, Ford Motor Co., General Motors, BMW and other automakers favor urea, an ammonia-based acid, to reduce NOx, a precursor of smog. The system, also called selective catalytic reduction, is seen as the best way to enable widespread use of diesels in North America, Europe and Japan. It enables diesel engines to meet the most stringent emissions standards in all countries.

The EPA guidelines will be issued as early as October, said Margo Oge, director of the EPA's Office of Transportation and Air Quality. She was in Detroit last week to address a diesel engine and emissions conference.

The guidelines for urea injection systems are expected to be used on diesel-powered cars and trucks starting in 2010. All diesels sold in the United States after Jan. 1, 2010, must meet Tier 2 Bin 5 levels of emissions, just like gasoline engines.

Running on empty

Oge would not talk specifically about the guidelines. But she said disabling the car's engine when the urea tank is empty is a possibility. Automakers oppose preventing the engine from starting when the urea tank is empty, citing safety issues.

Oge says the EPA doesn't want to endanger drivers by having their engines turn off when the urea tank runs dry. But she said the EPA cannot allow vehicles that do not meet emission standards to be driven.

Once the guidelines are published, automakers will have a chance to petition the EPA for changes.

Cost-effectiveness is a key reason most automakers are working on urea systems. Kevin McMahon, managing partner at the Martec Group, a Detroit research and consulting firm, said it should cost automakers about $880 to equip a diesel-powered vehicle with a urea system. The alternative, McMahon, said is a NOx trap in the exhaust system that costs about $1,400.

The rules will address the main problem regulators have with urea: The system won't work unless an on-board urea tank is replenished. Otherwise, the car won't meet emissions standards.

The EPA is considering rules that will require the vehicle to eventually stop running if drivers don't keep the tank filled.

Karl Simon, the EPA's assistant director for the office of transportation and air quality, said the agency is focusing on an early-warning system that notifies drivers when the urea tank is low.

The agency also is considering an inducement that forces drivers to refill the urea tank - for example, preventing the engine from starting if the tank is empty or automatically locking the fuel filler door until the urea supply is replenished.

The agency says automakers will have to make it easy for drivers and technicians to identify the urea tank and refill it.